Prefeeder mechanism for single facer machines



Nov. 18, 1969 H. w. MOSER 3,479,240

PREFEEDER MECHANISM FOR SINGLE FACER MACHINES Filed Aug. 5, 1964 2 Sheets-Sheet l mvcu'ronz HENRY W. MOSER ATTYS.

H. w. MOSER 3,479,240

PREFEEDER MECHANISM FOR SINGLE FACER MACHINES Nov. 18, 1969 2 Sheets-Sheet 2 Filed Aug. 5, 1964 mvcn'roa: HENRY W. MOSER United States Patent 3,479,240 PREFEEDER MECHANISM FOR SINGLE FACER MACHINES Henry W. Moser, Haddonfield, N.J., assignor to Harris- Intertype Corporation, a corporation of Delaware Filed Aug. 3, 1964, Ser. No. 386,887 Int. Cl. B65h 23/18; B31f 1/28 US. Cl. 156-205 8 Claims ABSTRACT OF THE DISCLOSURE The present invention relates generally to machinery for producing corrugated paperboard and more particularly to apparatus for prefeeding paper medium mm the corrugating rolls of a single facer machine.

The manufacture of single faced corrugated paperboard, which comprises a corrugated paper medium glued to a flat paper liner, has heretofore been a limited speed operation because of the tendency of the paper medium to fracture at the corrugating rolls at higher speeds. Although the inherently non-uniform tensile strength and bending qualities of the paper medium contribute to the tendency of the medium to fracture during the corrugating operation, the principal cause of fracturing is the frequent and sudden variations in tension of the medium web entering the corrugating rolls. The tension variations may be attributed to an unbalanced condition of the supply roll, the flywheel effect of a large diameter supply roll, the changing diameter of the supply roll as the paper is unwound, and an uneven braking action at the roll stand. Further variations in tension result from changes in operating speed of the single facer unit, and the passage of the medium through the preconditioning equipment conventionally employed with single facer units.

The corrugating roll flutes have heretofore in the usual installation acted to pull the paper medium into the rolls against the varying tension. However, since the medium travels at a faster surface speed than the periphery of the corrugating rolls because of the corrugating action taking place at the nip of the rolls, the medium is dragged over the flutes of one of the rolls and is bent sharply around the flutes which are just coming into mesh. The tensile and bending stresses are thus extremely high at the nip of the corrugating rolls and increase rapidly with an increase in the speed of the single facer machine. Although fracturing of the medium normally occurs at the nip of the corrugating rolls where the stresses are highest, the medium is substantially weakened prior to reaching the nip by the dragging thereof over the roll flutes while subjected to the frequent and sudden varia tions in tension.

The present invention provides a means for prefeeding the medium to the corrugating rolls such that the medium as fed to the rolls is under a light, constant tension which prevents the stresses on the medium occasioned by the dragging of the medium over the roll flutes under abruptly changing tension.

It is accordingly a primary object of the present invention to provide a prefeeding means for single facer machines which permits a higher speed of operation of the single facer machine with a given grade of medium than previously permissible.

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A further object of the invention is to provide a prefeeding means for a single facer which automatically maintains a substantially low tension of the paper medium within desired narrow limits as it enters the corrugating rolls regardless of variations in tension of the web traveling from the supply source.

An additional object of the invention is to provide a prefeeding means of the type described which may be quickly and easily adjusted during operation to suit changing physical characteristics of the paper medium employed.

Another object of the invention is to provide a prefeeding means as described which is of a simple construction and which may be economically adapted to existing single facer machines.

Additional objects and advantages of the invention will be more readily apparent from the following detailed description of embodiments thereof when taken together with the accompanying drawings in which:

FIG. 1 is a schematic side elevational view of apparatus in accordance with the present invention shown in conjunction with a conventional single facer unit; and

FIG. 2 is a schematic side elevational view of a second embodiment of the invention similarly shown in conjunction with a conventional single facer machine.

Referring to the drawings, FIG. 1 shows schematically a single facer machine including upper and lower corrugating rolls 10 and 12 mounted for cooperative action with respect to the paper medium 14 passing therebetween. The corrugating rolls are driven in rotation by a suitable drive means such as an electric motor (not shown) and in turn drive the variable speed drive mechanism 16 connected therewith by drive chain 17. Associated with the corrugating rolls in the usual manner are the glue applicator roll 18 and the doctor roll 20 which are mounted to apply glue 21 from the glue pan 22 to the flutes of the corrugated medium passing around the underside of the second corrugating roll 12. A pressure roll 24 coacts with the lower corrugating roll 12 to apply the liner 26 passing therearound from the rolls 28 and 30 onto the corrugated medium. Idler roll 32 is provided for guiding the single faced paperboard product from the single facer unit. The above-described apparatus represents a well known construction of single facer machines.

The present invention comprises, in the embodiment of FIG. 1, the prefeeding apparatus generally designated 36 positioned in the path of the paper medium 14 ahead of and immediately adjacent the corrugating rolls 10 and 12. The prefeeding apparatus 36 includes a pair of closely spaced prefeeder rolls 38 and 40 which are positioned so that the paper medium engages a substantial portion of the peripheral cylindrical surface of each roll with the opposite sides of the medium contacting the respective roll surfaces. The prefeeding rolls 38 and 40 are preferably smooth surfaced rolls which are driven by means of the prefeeder drive chain 42 connected with the variable speed drive 16. The roll 38 is slightly larger in diameter than roll 40. Although the rolls 38 and 40 have respective gear faces 44 and 46 for positive rotation thereof in opposite directions, the prefeeder roll surfaces which engage the paper medium are not in contact and the prefeeding eifect provided by the rolls results solely from the frictional engagement of substantial peripheral areas of the rolls with the paper medium.

The single facer apparatus is operated in a conventional manner with the paper medium passing into the nip 48 of the corrugating rolls 10 and 12 wherein it is corrugated by the meshing roll flutes. The corrugated medium passes around the lower corrugating roll 12 and the flutes thereof are coated by the applicator roll 18 with glue 21 from the glue pan 22. The liner 26 is then applied to the glue-wetted flutes of the corrugated medium by the pressure roll 24. The single faced paperboard product 34 passes from the single facer over idler roll 32.

The prefeeder rolls 38 and 40, which alternately engage the opposite sides of the medium ahead of the corrugating rolls, are driven at a slightly higher surface speed than the speed of the paper medium that is being fed or pulled into the single facer corrugating rolls. The speed dif ferential is controlled by the variable speed drive mechanism 16. The higher surface speed of the prefeeder rolls, which may be for example 1% to 2% greater than that of the paper medium, is essential to maintain automatically a low tension condition of the paper medium in the region 50 between the prefeeder rolls and the corrugating rolls. The speed differential insures a low medium tension at the corrugating rolls but will not permit a slack condition of the medium since, as the medium tension decreases, the frictional engagement of the medium with the prefeeder rolls decreases and permits slippage of the prefeeder rolls with respect to the medium. This arrangement thus automatically controls the medium tension to provide a desired low tension within very narrow limits at the corrugating rolls, the overfeed of the prefeeder rolls preventing tensioning in this region and the diminution of frictional engagement with the prefeeder rolls preventing a slack medium condition. It is essential that a certain low tension be maintained adjacent the corrugating rolls so that the medium will track properly on passing through the corrugating rolls rather than weaving from side to side at the nip 48 of the rolls.

It is difficult to make rolls with substantially equal or identical diameters and if roll 38 is even .0005" smaller in diameter than roll 40, there is a possibility that the tension in the paper medium between these rolls 38 and 40 will increase over a period of time. For this reason, the roll 38 is slightly larger than the roll 40 to prevent this tension from ever building up excessively between these prefeeder rolls. The automatic control of tensioning in the medium between rolls 38 and 40 will then be maintained in the same way that the tension in the medium between roll 40 and is maintained.

The second embodiment of the invention, illustrated in FIG. 2, is shown in conjunction with a single facer machine having the same basic construction as that illustrated in FIG. 1, the components of which are designated by the same identifying numbers with the suffix a. The single facer of the second embodiment operates in the manner described above and the differences between the embodiments reside solely in the construction of the prefeeder apparatus.

The prefeeder apparatus 54 of the second embodiment comprises a single prefeeder roll 56 which is driven in rotation by the adjustable drive mechanism 16a by means of the drive chain 58. The paper medium 60 is maintained in contact with a substantial area of the peripheral surface of the prefeeder roll 56 by means of the adjustable idler roll 62 and the dancer roll 64. The position of the idler roll 62 may be adjusted by means of the idler roll rack 66 pivotable coaxially with the prefeeder roll 56 and controlled by the positioning gear 68. The dancer roll 64 is supported by brackets 70 pivotable about the axis of the prefeeder roll 56 and which permit free movement of the dancer roll between the stops 72 and 74.

The operation of the second embodiment is quite similar to that of the embodiment previously described, with the prefeeder roll 56 being driven at a faster surface speed than the speed of the paper medium that is being fed into the corrugating rolls 10a and 12a. The medium 60 is advanced by frictional engagement with the prefeeder roll 56, which engagement requires a low minimum ten sion of the web along the medium run 76 leading to the upper corrugating roll to effect a prefeeding action. Should the tension along the run 76 adjacent the corrugating roll 10a fall below the required minimum, the

frictional engagement will be insufficient to advance the medium at the prefeeding roll speed and slippage will occur until the tension of the medium is restored to the desired value which maintains the proper tracking of the medium through the corrugating rolls. The described compensating action takes place continuously and almost imperceptibly to effect a substantially constant low tension of the medium as it enters the corrugating rolls.

As in the first embodiment, the medium, upon passage throughthe corrugating rolls 10a and 12a, contacts the glue applicator roll 18:: and is joined to the liner 73 upon passage between the pressure roll 24a and the lower corrugating roll 12a to form the single faced product 80.

The use of the single prefeeder roll 56 with the adjustable idler roll 62 provides flexibility for prefeeding a wide range of grades of paper medium. The idler roll may, for instance, be moved from the position shown to that illustrated in broken lines at 82 to decrease the angle of engagement of the medium with the prefeeder roll, which adjustment will substantially increase the tension maintained on the medium run 76 entering the corrugating rolls. By adjustment of the idler roll position, the traction of the prefeeder roll may thus be effectively varied to provide the desired medium tension at the corrugating rolls depending upon the characteristics of the particular medium being run. With either of the illustrated embodiments the corrugating rolls have only to provide a sufficient take-up tension to insure that sufiicient traction is effected by the prefeeder rolls to accomplish the prefeeding function and to insure that the paper tracks properly through the corrugating rolls.

As indicated above, the best operating results and highest operating speeds are obtained by holding the medium tension at the corrugating roll nip at a minimum and it has been found that an optimum minimum tension should be in the order of /4 lb. per inch of paper width.

The present invention not only allows a substantial increase in the permissible operating speed of the single facer with good quality paper but also permits the approaching or surpassing of present operating speeds with inferior grades of paper which heretofore could not be run economically because of the limited speed with which they had to be run to produce acceptable single faced corrugated paperboard. The runability (a term frequently used in referring to the maximum speed at which a paper medium can be run without having more than one fracture per four square feed of medium) of the various mediums commonly employed has, in tests of the present apparatus, been increased substantially, the runability of one medium being increased to over six times the speed previously considered limiting.

The present invention makes possible the use of corrugating rolls with a tooth contour which produces a lower ratio, known in the trade as the take-up ratio, between the amount of paper medium used for making up the corrugated web with respect to the amount of paper liner applied to it. Such a lower take-up ratio not only results in a saving in the amount of paper medium used, but in addition the strength of the board produced with lower ratio tooth contours is, surprisingly, in many instances increased rather than adversely affected.

Manifestly, changes in details of construction can be effected by those skilled in the art without departing from the spirit and the scope of the invention.

I claim:

1. A method of controlling tension in a web medium just prior to introduction of the medium into the corrugating rolls of a single facer comprising, unwinding the medium from a parent roll, frictionally feeding the unwound medium to corrugating rolls, corrugating the medium at said rolls, controlling the tension in the medium by using at least one prefeeder roll to perform said feeding step, said feeding step including rotating the prefeeder roll at a surface speed greater than that of the speed of the medium as it enters the nip of the corrugator rolls, and said feeding step including effecting engagement of the medium with a substantial area of said prefeeder roll to provide a frictional prefeeding depending on the tension of the medium between the prefeeder roll and the corrugating rolls.

2. Apparatus for prefeeding a paper medium into the corrugating rolls of a single facer machine comprising a prefeeder roll positioned ahead of and adjacent the corrugating rolls, means for rotating said prefeeder roll at a uniform surface speed always greater than the speed f the paper medium being fed into the corrugating rolls, and means for effecting engagement of the medium with a substantial area of said prefeeder roll to provide a frictional prefeeding of the medium depending upon the tension of the medium between the prefeeder roll and the corrugating rolls so that the speed differential between said prefeeder roll and the paper medium effecting a continuous, automatic control of the medium tension.

3. Apparatus for prefeeding a paper medium into a single facer machine to provide a substantially constant low tension of the medium entering the single facer corrugating rolls, said apparatus comprising a prefeeder roll positioned ahead of and adjacent the corrugating rolls, means for rotating said prefeeder roll at a surface speed greater than the speed of the paper medium being fed into the corrugating rolls, and means for effecting frictional engagement of the medium with a substantial peripheral area of said prefeeder roll prior to passage thereof into the corrugating rolls, said latter means providing for the frictional engagement of the medium with the prefeeder roll to vary directly with variations in tension of the medium between said prefeeder roll and corrugating rolls and thus to automatically regulate the feeding action of the prefeeder roll, an increase in medium tension resulting in an increased frictional engagement with the prefeeder roll to provide an increased surface speed of the medium at the prefeeder roll and hence a decreased medium tension, a decrease in medium tension resulting in a decreased frictional engagement permitting slippage between the prefeeder roll and medium to restore the desired low medium tension.

4. Apparatus for prefeeding a paper medium into a single facer machine to provide a substantially constant low tension of the medium entering the single facer, said apparatus comprising corrugating rolls, a pair of closely spaced prefeeder rolls one larger than the other and positioned ahead of and adjacent the corrugating rolls, means for rotating said prefeeder rolls at a surface speed greater than the speed of the paper medium being fed into the corrugating rolls, and means including said close spacing of the prefeeder rolls for effecting frictional engagement of the medium with a substantial peripheral area of each of said prefeeder rolls prior to passage thereof into the corrugating rolls, said prefeeder rolls being so positioned with respect to the path of travel of the medium passing into the corrugating rolls as to permit the tension of the medium between said prefeeder rolls and corrugating rolls to control the frictional engagement of the medium with the prefeeder rolls and thus automatically regulate the prefeeding action of the prefeeder rolls, an increase in medium tension resulting in an increased frictional engagement with the prefeeder rolls to provide an increased surface speed of the medium at the prefeeder rolls and hence a decreased medium tension, a decrease in medium tension resulting in a decreased frictional engagement permitting slippage between the prefeeder rolls and medium to restore the desired low medium tension.

5. The invention as claimed in claim 4 wherein said means for rotating said prefeeder rolls at a surface speed greater than the speed of the paper medium being fed into the corrugating rolls comprises a variable speed drive means driven by said corrugating rolls providing for accurate adjustment of the speed differential between the paper medium and said prefeeder rolls to suit the characteristics of a medium being processed.

6. Apparatus for prefeeding a paper medium into a single facer machine to provide a substantially constant low tension of the medium entering the single facer, said apparatus comprising corrugating rolls, a prefeeder roll positioned ahead of and adjacent the corrugating rolls, means for rotating said prefeeder roll at a surface speed greater than the speed of the paper medium being fed into the corrugating rolls, and means for effecting frictional engagement of the medium with a substantial peripheral area of said prefeeder roll prior to passage thereof into the corrugating rolls, said latter means comprising an idler roll positioned ahead of and adjacent said prefeeder roll and a dancer roll adjacent said prefeeder roll between said prefeeder roll and the corrugating rolls, said latter means providing for the tension of the medium between said prefeeder roll and corrugating rolls to control the frictional engagement of the medium with the prefeeder roll and thus to automatically regulate the feeding action of the prefeeder roll, an increase in medium tension resulting in an increased frictional engagement with the prefeeder roll to provide an increased surface speed of the medium at the prefeeder roll and hence a decreased medium tension, a decrease in medium tension resulting in a decreased frictional engagement permitting slippage between the prefeeder roll and medium to restore the desired low medium tension.

7. The invention as claimed in claim 6 including means for angularly adjusting the position of said idler roll about the periphery of said prefeeder roll to vary the peripheral area of engagement of the medium with the prefeeder roll in accordance with the characteristics of a paper medium being processed and the tension of the medium desired at the corrugating rolls.

8. The invention as claimed in claim 6 wherein said means for rotating said prefeeder roll at a surface speed greater than the speed of the paper medium comprises a variable speed drive means driven by said corrugating rolls providing for accurate adjustment of the speed differential between the paper medium and said prefeeder roll to suit the characteristics of a medium being processed.

References Cited UNITED STATES PATENTS HAROLD ANSHER, Primary Examiner H. E. EPSTEIN, Assistant Examiner US. Cl. X.R. 

